Just wondering what causes broken valve springs? I am interested in anyones experience with having the "fortunate" experience of having a broken spring and what the carnage was from it.

 

The only causes I've seen for a broken spring was a defect in the spring metal. Only carnage I've seen was a bent valve since the keeper was still in the retainer.

Now if the spring drops down far enough to allow the keepers to fall out. Look out.

 

i got the engine in my trans am hot a few times cause the headgasket was on its way out.. found out one of my 10308's was broken. when trying to fix it. it didn't do anything to the motor cause its a dual spring but it never seemed to be lacking power or any decrease at anytime. threw out all the springs and bought new.

 

coil bind

 

at 1500 RPM?

 

Coil bind and faulty springs. I had 3 Comp 918's bust in 20 miles a few years ago. Those were the faulty blue stripe cheap Mexican made springs.

 

Do they still consider heat cycles in new valve springs as break-in or has advancements in manufacturing and materials eliminated that?

 

You should still "break in" the springs with a heat cycle at low rpm followed by a full cool-down. This is specifically noted in new boxes of many high performance springs. Most common failure causes I have seen are revving while cold on H-11 high pressure springs, being set up at coil bind, spring defect, poor valve control harmonics.

 

It's pretty much been covered. The commonest cause is a defect in the material. Eventually, they will work harden, become brittle and fail. How soon this happens depends on operating conditions (heat, rpm, etc.), number of cycles, quality of the materials, etc.

Rich

 

I have observed a similar problem in a rally car operation.
Further observation showed that the timing belt was fluttering and twisting by almost 90 degrees.
Does the belt or the cam oscillations also cause valve spring failure?

If yes, then what could be the cause for these oscillations?

 

find any valuables digging?